The specific aims of this study are: 1) to examine the effect of low-fat dietary intervention on estradiol, free estradiol, and sex-hormone binding globulin (SHBG). 2) To examine the effect of low-fat dietary intervention on markers of bone turnover. 3) To determine if the impact on bone remodeling is due to the mgnitude of change in estradiol or the absolute level of bio-available estradiol.